Abstract: OBJECTIVE To explore the value of circulating free DNA (cf-DNA) combined with 16S ribosomal RNA (16S rRNA) gene detection in early diagnosis of patientsd with diabetic burn sepsis. METHODS A total of 65 diabetic burn patients who had suspected sepsis and were treated in burns department of Binzhou People Undefineds Hospital from Mar. 2016 to May 2018 were enrolled in the study, the conventional blood culture was performed and the 16S rRNA gene detection was carried out for identification of bacteria by PCR. The correlation between PCR, result of blood culture and the indexes was observed. RESULTS The 16S rRNA gene detection showed that 30 of 65 specimens were positive, with the positive rate 46.15%; 18 patients were positive for blood culture, with the positive rate 27.69% (P<0.05). The time of the PCR detection was significantly shorter than that of the conventional blood culture (P<0.05). Totally 19 (63.33%) strains of gram-negative bacteria and 11 (36.67%) strains of gram-positive bacteria were isolated by PCR; totally 13(72.22%) strains of gram-negative bacteria and 5 (27.78%) strains of gram-positive bacteria were isolated by blood culture. The levels of cf-DNA, C-reactive protein (CRP), tumor necrosis factor(TNF-α), interleukin-6 (IL-6), fasting blood glucose(FBG) and 2h postprandial blood glucose (2h PG ) of the PCR-positive patients were significantly higher than those of the PCR-negative patients (P<0.05). The cf-DNA level was positively correlated with the levels of peripheral blood CRP, TNF-α and IL-6 (P<0.05). The levels of cf-DNA, CRP, TNF-α, IL-6, FBG and 2hPG of the patients positive for blood culture were significantly higher than those of the patients negative for blood culture (P<0.05). CONCLUSION The PCR detection of 16S rRNA gene may rapidly identify the pathogens causing infection in the diabetic burn sepsis patients, and its combination with cf-DNA may facilitate the early diagnosis of the diabetic burn sepsis.